Electrical signal device and system



Dec. 22, 1936: 1 WHEELOCK I 2,065,409

ELECTRICAL SIGNAL DEVICE AND SYSTEM Filed Nov. 10, 1953 Inventor J n H. wheelbck Aiiorn ey Patented Dec. 22, 1936 UNITED STATES PATENT OFFICE Signal Engineering & Manufacturing Company, New York, N. Y., a corporation of Massachusetts Application November 10, 1933, Serial No. 697,417

1 Claim.

The present invention relates to electrically operated signals, and has for its object to provide improved signal devices and a system particularly adapted for use in connection with existing telephone installations for the purpose of signaling incoming calls in a manner different from that of 'the telephone bells usually employed.

It is well known that the sounds made by ordinary telephone bells, or buzzers, actuated by telephone ringing current are more or less unpleasant and even objectionable under some circumstances. At the same time, it is a fixed policy of most telephone companies to discourage the use of signaling devices other than standard bells or buzzers, or any attempts to choke the sound given off by the usual telephone bells; the obvious reason being that an essential function of any telephone installation is to secure attention to any and all incoming calls.

According to the present invention there are provided auxiliary signaling devices or units for use in connection with existing telephone installations, with each unit obtaining its operating current from a. source independent of the telephone installation, such as any light or power circuit, while receiving its primary ener-gization from telephone ringing current. Furthermore, each auxiliary signal unit is so connected with relation to the bell of the existing telephone installation, 3 that while the auxiliary signal will ordinarily be operated in place of the telephone bell, the latter will be automatically rendered operative upon any failure of the source from which the auxiliary signal is operated, or upon disconnection of the unit from this source. That is to say, the transmission of telephone ringing current from the central station to the subscribers station will always result in either operating the auxiliary signal, or the usual bell or buzzer. The above and other advantageous features of the invention are more fully set forth in the following description with reference to the accompanying drawing, in which:-

- Fig. 1 is a general wiring diagram, illustrating the manner of installing a system of auxiliary signal units in connection with several telephone subscribers stations.

Fig. 2 is a View showing on an enlarged scale the construction of one of the auxiliary signal units. Fig. 3 is a view similar to Fig. 2 illustrating a modification of the invention.

Like reference characters refer to like parts in the different figures.

Referring first to Fig. 1, there is illustrated diaor I grammatically, a number of telephone subscribers stations S, each providing the usual telephone instrument as indicated, and a subscribers equipment box B including a bell, all of usual construction. For the sake of simplicity, the complete wiring of the telephone sets of the subscribers station S is simplified to the extent of showing only conductors b leading to each box from the central exchange C, with ringing means indicated at K associated with the conductors I), see Fig. 2. As is usual, the conductors b are adapted to be energized at the central station C, so that telephone ringing current is transmitted to any box of a subscribers station S upon operation of the ringing means K at the central station.

Associated with each subscribers station S is a portable auxiliary signal unit I, preferably of the single stroke chime type, as will be hereinafter described. Each signal unit 1 provides a cable 2 carrying at its end a suitable plug 3 for insertion in a power outlet 4 located adjacent to the subscribers station S, each outlet 4 being energized from. the mains 5 of a wiring installation, such as is usually provided for furnishing light and power to the building in which the subscribers telephone set S is located. Each signal unit I also provides a multiple conductor cord 6 having a number of tips I for convenient connection to a terminal block 8 on the subscribers instrument box B. When installing a signal unit I at any subscribers station S, it is only necessary to mount the unit adjacent to the nearest box B and power outlet 4, as by means of suitable wall studs la, see Fig. 2, installation of the signal unit I being completely accomplished by inserting its plug 3 in the outlet 4 and connecting the conductors of the cord 6 to the box terminal block 8. Obviously, suitable telephone plugs and jacks, or any other similar connecting means, may be substituted for the conductor tips 1 and block 8.

Referring now to Fig. 2, one illustrative embodiment of the type of signal unit employed in connection with each subscribers station S consists of a resonant chime member 9 disposed in the path of movement of a magnetic plunger l0 movable axially within an operating winding ll of the solenoid type. With the winding II in a deenergized condition, the plunger 10 is only partially disposed within the surrounding solenoid, so that energization of the latter is adapted to draw the plunger l0 upwardly to strike the resonant chime member 9 a single sharp blow. One terminal of the winding l l is connected directly to one of the conductors 2a of the cable 2, while the other winding terminal is connected 5;;

to one of a pair of spaced stationary contacts l2. The other contact I2 is connected to the second power cable conductor 22), so that normally there is a gap in the circuit of the winding ll between the spaced contacts [2. Therefore, insertion of the plug 3 of the power cable 2 into an outlet 4 does not energize the winding ll, but merely establishes a condition in which this winding will be energized upon bridging of the contacts 12 by a member l3 carried by an armature [3a under the control of an auxiliary winding M of the signal unit. One terminal of this auxiliary winding I4 is connected through a condenser to one conductor 6a of the cord 6 leading to the box B, while the other terminal of winding 14 is connected to one of a pair of spaced stationary contacts [5. The other contact [5 is connected to a second conductor 6b of the cord 6 leading to the box B, so that when the space between the contacts I5 is closed by a bridging member IS, the terminals of the winding M are connected across two line terminals LI and L2 of the box B through the conductors 6a and 6b in circuit with the condenser.

The bridging member I6 is carried by an armature lBa under the control of a winding [1, the terminals of which are connected across the conductors 2a and 2b of the power cable 2. With the winding IT energized, due to the' insertion of the plug 3 in the power outlet 4 as shown in Fig. 2, the bridging member 16 is held in engagement with the spaced stationary contacts l5, thereby maintaining the connection of the auxiliary signal winding M to the box B through the conductors 6a and 6b.

The equipment in the box B is of any usual type, and is shown as providing bell ringing coils [8, which upon energization by a ringing current, will cause the subscribers bell to ring. One terminal of the ringer coils I8 is connected through a box condenser to box line terminal L2, which in turn is connected to one conductor 27 leading from the ringing means K, while the other ringer coil terminal is connected to the third conductor 6c of the cord 6. The conductor 60 is connected to one of a pair of spaced stationary contacts I9, the other of which is connected to the conductor 6b in parallel with the contact IS. The gap between the spaced contacts I9 is adapted to be closed by the bridging member I6 upon deenergization of winding l'l, so that the conductor 6b which is connected permanently through box line terminal Ll to the other conductor 2) from the ringing means K is adapted to transmit ringing current either to the auxiliary signal winding 14, or to the ringer coils l8, depending upon the position of the bridging member IS with reference to the cooperating pairs of spaced contacts l5 and l9.

With the plug 3 of the signal unit I located at the subscribers station S in Fig. 2 inserted in a power outlet 4, it is obvious that the terminal of the ringer coils l8 connected to the contact H! by conductor 60 will be maintained disconnected from the return conductor 6b, due to the gap between the spaced contacts 19. Therefore, when the ringing means K is operated to supply ringing current to this particular subscribers station S, the bell will not be rung. On the contrary, the ringing current will pass from conductor 61) through the bridged contacts 15 to energize the auxiliary signal winding l4, thereby causing the movable contact member l3 to bridge the stationary contacts l2. Closure of these contacts [2 completes the connection of the main signal winding ll across the conductors 2a and 2b of the power cable, whereupon the plunger 10 moves upwardly to strike the resonant chime member 9 a single sharp blow, the plunger l remaining in this striking position as long as ringing current is applied. The sound emitted by the resonant member 9 is of a clear penetrating quality, and a single stroke thereon is sufficient to call the subscribers attention to the fact that there is an incoming call. In case the subscriber does not answer immediately, subsequent re-applications of the ringing current, as is the usual practice, results in reenergizations of the winding II to again sound the chime. Obviously, recurrent strokes of the chime will be much less disturbing to the ear than the continued ringing of the bell in the box B during the full period of application of ringing current from the central station C.

Upon failure of the source supplying the mains 5, or upon disconnection of the signal unit from the outlet 4, the deenergization of the winding I'I will result in two things:first, dropping back of the bridging member I 6 to engage the spaced contacts I 9 will establish the circuit of the ringer coils l8 from the conductor 60 to the conductor 6b,second, disengagement of the bridging member Hi from the contacts l will entirely disconnect the auxiliary signal winding l4 from the conductor 6b. Therefore, when ringing current is applied with the winding l1 deenergized, only the ringer coils 18 will be energized to sound the bell, and there will be no ringing current drawn by the winding !4. Since upon reenergization of the winding I! from the mains 5, the circuit of auxiliary winding M will be re-established, and the circuit from the ringer coils I8 will be broken as before, it follows that the auxiliary signal winding l4 and the ringer coils l5 can only be energized separately.

Referring now to Fig. 3, there is shown a modification of the invention, in which the auxiliary signal unit is connected for a two-party line, as distinguished from the connections for an individual subscribers line shown in Fig. 2. In addition, Fig. 3 also illustrates the manner in which power delivered to the winding ll controlling energization of the ringer coils may be limited in the event of a short circuit between the winding terminals,provision also being made for reducing the possibility of any disturbance of the telephone circuits through magnetic induction from the mains 5.

As shown in Fig. 3, one terminal of the winding I4 is grounded at G, so that telephone ringing current coming from the box B over the conductor So will pass to ground G through the winding [4, with the contacts I5 bridged as shown. One of the spaced stationary contacts IQ for controlling the ringer coils I8 is also connected to ground at G, in parallel with winding 14, so that when the contacts I9 are bridged by member l6 upon deenergization of winding ll, the terminal of the ringing coils l8 connected to the conductor 60 will be connected to ground and the bell will be rung. Therefore, the functioning of the devices shown in Fig. 3 will be substantially the same as described with reference to Fig, 2, with the exception that ringing current comes from the central station C over a single conductor b and passes to ground either through the auxiliary signal winding 14, or through the ringer coils IS in accordance with the position of the bridging member 16'.

In order to eliminate any possibility of the telephone ringing circuit being directly connected to the power mains 5, the arrangement of Fig. 3 also rovides for energization of the winding H from the secondary winding 20 of a transformer embodied in the signal unit, the primary winding 2| being connected across the conductors 2a and 2b of the cable 2. Preferably the transformer design is such as to limit the maximum power which may be delivered by its secondary winding 20, so that accidental connection of this secondary circuit to the ringing circuit will cause no damage to the telephone apparatus. In order to still further reduce the possibility of any disturbance of the telephone circuits through magnetic induction from mains 5, a suitable shielding barrier 22 of non-magnetic material may be provided around the winding Il, in

order to prevent any possibility of magnetic cou-' pling between windings I1 and I4. Since the winding ll, normally, is continuously connected to power mains 5 which may carry alternating current, or superimposed noises from generating equipment, the barrier 22 prevents these disturbances from being introduced into the telephone talking circuits through the winding I4. While such noise currents would cause no damage to telephone apparatus, they might be sufficiently strong to interfere with weak telephone voice currents, so that the barrier 22 eliminates even this possibility.

From the foregoing, it is apparent that by the present invention there is provided an improved signal unit and system that is particularly adapted for use in connection with existing telephone installations for the purpose of indicating incoming calls at any subscribers station in a more pleasing and effective manner than that afforded by the usual telephone bell. Obviously, the installation of my improved signal unit at a subscribers station is readily effected by merely plugging in the unit at the nearest power outlet and connecting its three-conductor cord to the telephone bell. In other words, no changes are necessary in either the existing power wiring or telephone installation. The installation of a signal unit in no way affects the ability of the central station operator to send any call, for as long as the ringing circuit is intact, the closure of the ringing key will result in either sounding the chime signal, providing the latter is connected to the power circuit, or sounding the usual telephone bell in the event of power failure, or disconnection of the chime signal unit from the power circuit.

I claim,-

In a telephone system, the combination with a source of ringing current, a telephone ringer at a subscriber's station and a source of commercial power, of a signal device providing a resonant member, a magnetic plunger and an operating solenoid having one terminal connected to said power source, a control winding energizable from said ringing current source to connect the other terminal of said solenoid to said power source, and a second control Winding energizable from said power source for maintaining said ringer disconnected from said ringing current source, with each application of ringing current serving to energize said solenoid and cause its plunger to strike the resonant member a single blow, while said ringer remains disconnected from said ringing current source by the continued energization of said second control Winding from said power source.

JOHN H. WHEELOCK. 

